[Note:  You may download the "Requirements for the Certification of DMIS Software" document directly from this link.]

Contents:

I. What is DMIS?

II. What is the DMIS Certification Program? 

1. What does Conformance to the DMIS Standard Mean?
2. DMIS Conformance Testing. 
3. The NIST DMIS Test Suite (NDTS)

III. What is the Certification Process? 

IV. What are the Steps for Certification? 

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I.  What is DMIS?
DMIS (Dimensional Measuring Interface Standard) is both an American National Standard and ISO international standard language for the correct, complete, and unambiguous description of computer-executable dimensional measurement part programs and measurement results.  (In fact, it is the only such standard.)  As an approved standard, DMIS is non-proprietary and represents industry consensus.  Dimensional measurement part programs and results are critical to manufacturing Quality Assurance.  Since DMIS is a very large standard, it has been divided up into a variety of conformance classes, in order to accommodate the fact that many implementers only need to implement portions, or subsets, of the DMIS standard. 

DMIS implementations fall into two categories: DMIS producers, and DMIS consumers.  DMIS producers generate DMIS input (DMI) files containing a list of DMIS instructions.  DMIS consumers read/interpret DMI files to execute actual measurements and produce measurement results such as DMIS output (DMO) files. 

DMIS is a successful, dynamic standard because its scope and capabilities have expanded over the years along with technology advances in the metrology industry.  However, this success has brought about challenges in the area of compliance of DMIS implementations.  Not surprisingly, of those who claim DMIS compliance, the actual compliance varies as widely as the implementations. 

In pursuit of better DMIS compliance in the Quality Industry, the Dimensional Metrology Standards Consortium (DMSC, Inc.), called upon NIST to mature their NIST DMIS Test Suite as a key mechanism of a DMIS Certification Program. 

II.  What is the DMIS Certification Program?

  Consider the situation if CMM users insisted on purchasing only CMM software that has DMIS Certification.  Part programs would be able to transition through CMM machine and software changes, and be interchangeable with partners, divisions, and suppliers around the world; thus having a much higher value, life-span, and use for the time and cost invested.
 
The DMIS Certification Program is a process whereby vendors and users of DMIS-based products can verify that these products actually conform to the DMIS Standard, thus enabling the interoperability of programs.  Timely, correct, complete, unambiguous, and widely-implemented non-proprietary interface standards save time and money for everyone from customers, to end users, tier suppliers, and vendors.

The benefits of non-proprietary interface standards are realized when end users and tier suppliers demand them and lead efforts to enable them. 

1. What does Conformance to the DMIS Standard Mean?
The primary purpose of DMIS is to allow organizations to exchange measurement programs and store measurement data among different dimensional measurement devices and computer applications within their companies, as well as with company divisions, contractors, or other companies and organizations.  DMIS is widely used and available for a broad range of measurement systems and applications.  However, a DMIS file that is created by one DMIS product may not be fully or correctly interpreted by another DMIS product.  Successful DMIS interchange can only be achieved if DMIS applications faithfully implement (1.) the DMIS standard, and (2.) the appropriate, formally recognized DMIS Application Profiles coupled with any addenda. 

As DMIS is a very large language, most applications only need to implement subsets of the standard.  These subsets are called ‘conformance classes’ which have been defined by the DMIS Standards Committee.  In order to conform to a given conformance class, a system using DMIS must fully implement the subset for that class.  Two Application Profiles (APs) have been defined: One for Prismatic parts, and one for Thin Walled parts.  Seven addenda have also been defined which are rotary tables, multi-carriage, contact scanning, IPV (in-process verification), QIS (quality information systems), measurement uncertainty, and soft-gauging.

Each application profile and addendum may be implemented at one of three levels.  According to the DMIS Standard, Level 1 is essential or required to meet the profile’s goals; Level 2 is considered important to meeting the profile’s goals; and Level 3, is beneficial to meeting the profile’s goals.  The NIST DMIS Test Suite includes an Excel spreadsheet, developed by the DMIS Standards Committee, that details all of the commands used in the DMIS language, and those which are required for each level of conformance. 

The primary benefit of any DMIS profile is the ability to insure interoperability through the use of validation tools against DMIS instances and certification services for applications.  Once an application has been certified, behavior of that application is predictable under the constraints of the profile level.  

2. DMIS Conformance Testing
DMIS conformance testing is a way of determining if a DMIS compliant product correctly implements the DMIS standard with its associated Application Profile.  Strictly speaking, the DMIS standard is an exchange file format.  However, the term "DMIS" is often used to include a generator (a hardware and software system with which a user can produce DMIS input files), an executor (a hardware and software system that reads DMIS input files, does what they say to do, and writes DMIS output files), as well as the metafiles (the actual DMIS input and output files).  Together, the generator, metafiles, and executor form a total DMIS system. 

Conformance to DMIS is therefore defined in terms of conformance to a particular Application Profile of DMIS.  Thus, the DMIS standard, in conjunction with an Application Profile, is necessary in order to test conformance of a total DMIS system. 

3. The NIST DMIS Test Suite (NDTS)
The NIST DMIS Test Suite provides utilities and test files for conducting conformance tests on DMIS input files (.dmi), computer systems that generate DMIS input files, and computer systems that execute DMIS input files.  However, for the current DMIS Certification, submitted programs will be tested only for conformance to proper DMIS syntax; that is, the correct use of commands and structure in the DMIS language.  The current testing process will not analyze input programs for semantics nor for execution performance; that is, the test will not try to evaluate what the program statements ‘mean,’ nor verify that the program does what it is supposed to do. 

The NIST DMIS Test Suite, which now applies to DMIS 5.1 and 5.2, is intended to be useful to both developers and users of DMIS systems, and in fact for developers of additional DMIS Test Suites and other parsers.  The purpose of the NIST DMIS Test Suite is to help developers and users easily conform to the DMIS language. 

One (or more) of the parsers in the Test Suite may be used to parse DMIS input files produced by a commercial system.  This test will determine if the syntax of the files is correct.  The parsers in the Test Suite will provide a description of each error found, and will continue through the errors in order to make a complete report. 
                                             
IV.  Requirements for Certification of DMIS Software
21 April 2010

Certification of DMIS producer (measurement planning) software

·         An applicant for DMIS producer software certification is required to

Specify

o    Specify a particular DMIS conformance class, consisting of an application profile with conformance level plus optional addenda with conformance level, for which the applicant seeks certification (e.g., Prismatic Level 2 with Rotary Table Level 3)

o    Specify the name and version of the producing software the applicant is seeking to have certified

o    Specify the NIST DMIS Postprocessor version against which the applicant is seeking certification

Prepare

o    Compile and link the specified version of the NIST DMIS Postprocessor with applicant’s software, or use the NIST DMIS Postprocessor as a post process application called from the applicant’s software, so that all DMIS statements produced by the applicant’s software are run through the NIST Postprocessor, which will clearly validate and reveal:

§  Any incorrect DMIS statements

§  If all statements are correct, the conformance class (or classes) to which the candidate DMIS part program conforms

§  If all statements are correct, any DMIS statements or portions of DMIS statements outside the specified conformance class

Demonstrate

o    Using the version of the software for which the applicant is seeking certification, conduct a certification demonstration, in person or on live interactive web audio/video, in the presence of a representative (or representatives) from the certifying organization, which demonstration consists of

§  Applicant generating DMIS output using applicant’s measurement planning software

§  Applicant displaying the DMIS statements which are the output of the software

§  Applicant displaying the output from the NIST Postprocessor software, whether passing or failing the NIST Postprocessor validation

§  Applicant displaying the modification of DMISMN and DMISMD statements with appropriate DMIS conformance class parameters if the application generating DMIS part program passes the NIST Postprocessor validation

·         An applicant for DMIS producer software certification is expected to ensure that all operations implied by the DMIS words in the specified conformance class are also operations implied by the DMIS statements found in the DMIS part program produced at the live demonstration

·         The DMSC will certify a version of the applicant’s producing software in a particular conformance class only when the certifying organization is satisfied that the applicant’s software at the live demonstration

o    Generates DMIS commands which are all correct DMIS

o    Generates no commands outside the conformance class (note: the software is not required to generate every command in the conformance class)

o    Executes all the measurement functions implicit in the conformance class

o    Modifies the DMISMN and DMISMD statements with the appropriate DMIS conformance class parameters

Certification of DMIS consumer (measurement plan execution) software

·         An applicant for DMIS consumer software/system certification is required to

o    Specify a particular DMIS conformance class, consisting of conformance level plus addenda, for which the applicant seeks certification

o    Specify the version of the software/system the applicant is seeking to have certified

·         The DMSC will define and generate a DMIS test package for each conformance class consisting of

o    DMIS input test files containing examples of all commands in the conformance class and no commands outside the conformance class 

o    An appropriate test part (or 3D part model)

o    Detailed behavior expected to be performed by the applicant’s DMIS consumer software/system

·         The DMSC-approved certifying organization, using the specified test part and test files, will certify the applicant’s software/system, after the certifying organization

o    Runs DMIS input test files on the applicant’s DMIS consumer software/system

o    Judges that the specified behaviors have been successfully performed on the applicant’s DMIS consumer software/system

The Certification is good for one year, and during that year the Certified company may submit a reasonable number of files for certification, or re-certification.